The film will pick up where An Unexpected Journey left off, with Bilbo Baggins (Martin Freeman) and co having narrowly escaped the clutches of the Pale Orc thanks to some conveniently handy eagles (aren't they ever?). There's still a long journey ahead of them - they've got to travel through the depths of Mirkwood, encounter a heap of Elves and Men, and find a way into the cavernous lair of the mighty dragon Smaug (voiced by Benedict Cumberbatch).

There are parts of the trailer fans will recognise from the book: the Elves and spiders of Mirkwood, the Dwarves' barrel-ride down-river, Laketown, the secret door in the side of the Lonely Mountain (if you regard any of these as life-ruining spoilers, we've got three words for you: read a book).

There are also some surprises that may have Tolkien purists gnashing their teeth: we never saw Gandalf (Sir Ian McKellen) and Radagast (Sylvester McCoy) never take on the evil Necromancer in The Hobbit, but then again Jackson's aim has always been to weave in elements of the wider Middle Earth mythology to bind this trilogy more closely to his Lord of the Rings series, so that makes sense. There's also a cameo by Legolas (Orlando Bloom) as a Mirkwood Elf - he was never mentioned by name in The Hobbit, but then again, he always referred to Mirkwood as his home in LOTR, so there's no reason why he couldn't have been around. We also can't help wondering if this'll add subtextual meaning to his rivalry and eventual friendship with the dwarf Gimli (John Rhys-Davies) in LOTR, given that Gimli's dad, Gloin (Peter Hambleton), is one of the dwarves he holds at arrow-point in The Desolation of Smaug.

The biggest talking point about this first trailer is the titular dragon - or rather, the general lack of him. Sure, we get seven or eight seconds of his head at the end, but where are Cumberbatch's dulcet tones?

The Hobbit: The Desolation of Smaug is on general release from Fri 13 Dec 2013.